1. Field of the Invention
This invention relates to a method of reducing the formaldehyde emissions from formaldehyde condensation polymers, particularly urea-formaldehyde polymers, to a resin solution incorporating a substance which reduces the formaldehyde emissions from formaldehyde condensation polymers and to foamed formaldehyde condensation polymers incorporating a substance which reduces the free formaldehyde emission therefrom.
2. Prior Art Relating to the Disclosure
The emission of formaldehyde vapor from particleboard, plywood and insulating foams and other materials made with or incorporating formaldehyde condensation resins, particularly urea-formaldehyde resins, is and continues to be a problem. Numerous methods have been proposed to reduce the formaldehyde emissions from urea-formaldehyde resins. For example, U.S. Pat. No. 4,129,533 discloses substituting one or more aryl dialdehydes having two to eight carbn atoms for 20 percent of the total aldehyde moieties of the urea-formaldehyde resin, the dialdehydes provided as a cross-linking solution at the time of final polymer formation. U.S. Pat. No. 3,979,341 discloses the use of furfuryl alcohol and resorcinol to reduce formaldehyde odor in urea-formaldehyde foams. U.S. Pat. No. 3,231,525 discloses preparation of urea-formaldehyde foams in which the formaldehyde odor is reduced by adding free urea to the hardener solution during manufacture of the foam. Large amounts of calcium lignosulfonates and mineral oil containing sodium silicate have also been advocated for reducing the aldehyde emission of urea-formaldehyde resins. Notwithstanding the methods which have been proposed, it still remains a problem to find a practical and economical means of reducing formaldehyde emission from urea-formaldehyde resins, particularly those used for producing urea-formaldehyde foams used for insulation purposes. Whatever is incorporated in the urea-formaldehyde resin solution must not adversely affect the desired end properties of the foam produced and must be compatible with the ingredients of the foam.